Tmobile. not getting gdr2 ffor htc 8x

I have an international htc8x. It is unlocked/unbranded. I never got updates since October 2013 which was the last time I got an update called portico. Therefore I cannot enroll in the dev. preview because it tells me to update to gdr2, and my phone tells me that I am up to date. Does anyone have the same problems?